Magnetic core apparatus

ABSTRACT

A magnetic core apparatus includes two arcs of magnetic material which are rotatably mounted with respect to each other within a holder. The arcs can be rotated into alignment for placement about conductors not having accessible ends and then locked thereabout by rotating the arcs out of alignment.

United States Patent [19.]

DAlessio [111 7 3,831,124 [451 Aug. 20, 1974 MAGNETIC CORE APPARATUS[75] Inventor: Alfonso Joseph DAlessio,

Rockaway, NJ.

[73] Assignee: Bell Telephone Laboratories Incorporated, Murray Hill,NJ.

22 Filed: Nov. 8, 1973 211 App]. No.: 413,878

[52] US. Cl. 335/298, 336/176 [51] Int. Cl. H01f 3/00 [58] Field ofSearch 335/296, 298; 336/175, 336/ 176 [56] References Cited UNITEDSTATES PATENTS 2,291,013 7/1942 Wheeler 336/176 X 7/1949 Smith 336/176 X4/1973 Schweitzer 336/176 X Primary Examiner-George Harris Attorney,Agent, or Firm-A. D. Hooper ABSTRACT A magnetic core apparatus includestwo arcs of magnetic material which are rotatably mounted with respectto each other within a holder. The arcs can be rotated into alignmentfor placement about conductors not having accessible ends and thenlocked thereabout by rotating the arcs out of alignment.

7 Claims, 5 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to magnetic core apparatus and moreparticularly to a magnetic core adapted for installation aboutconductors having no accessible end.

2. Description of the Prior Art There are many applications wheremagnetic cores must be installed around conductors and the like whichhave no readily accessible end over which the magnetic core can beslipped. In such applications the conductors must either be disconnectedto provide an accessible end or the magnetic core must be segmented toallow its installation about the conductors. A common practice has beento segment the core into two 180 degree parts or arcs which are theninstalled about the conductors in an abutting end-to-end configurationby a suitable bracket'or other mounting means. Such an arrangement hasdisadvantages including the relatively long time required forinstallation of the mounting brackets because of the numerous partsinvolved and the relatively poor magnetic coupling between the abuttingends of the two segments.

Accordingly, it is an object of this invention to provide a magneticcore apparatus which can be quickly installed about conductors having noaccessible end.

Another object is to simplify magnetic core apparatus for installationabout conductors having no accessible end.

SUMMARY OF THE INVENTION The foregoing objects and others are achievedin accordance with this invention by a magnetic core which includes twocircular arcs of magnetic material. Each arc has a groove in a facethereof anda rail such as an arc of low friction material is mounted inthe groove so that the arcs mate together but can rotate with respect toeach other on the rail. An arc snap ring snaps around the assembledmagnetic arcs. The ring includes two upstanding flanges which hold oneare and the rail stationary with respect thereto but allows the otherare to rotate with respect thereto. The rotatable arc is rotated intoalignment with the stationary arc to form a gap and permit installationof the core about a cable. Then the rotatable arc is rotated in the ringas much as 180 with respect to the stationary arc to close the gapthereby locking the core about the cable and providing a substantiallycontinuous circular magneticpath about the cable.

BRIEF DESCRIPTION OF THE DRAWING The invention will be more fullycomprehended from the following detailed description and accompanyingdrawing in which:

FIG. 1 is a perspective view of two magnetic arcs mounted in alignmentwith each other;

FIG. 2 is a perspective view of a snap ring or holder for mounting aboutthe arcs of FIG. 1;

FIG. 3 is a perspective view of the ring of FIG. 2 installed about thearcs of FIG. 1 whichremain in an aligned configuration; v 2

FIG. 4 is a perspective view similar to FIG. 3 with the are slightlyrotated with respect to each other; and

FIG. 5 is a perspective view similar to FIGS. 3 and 4 with the arcsrotated approximately with respect to each other.

DETAILED DESCRIPIION' FIG. 1 shows two arcs 2 and 4 of a magneticmaterial aligned with each other so as to produce a gap 6 between theends thereof through which a continuous conductor or the like can beinserted into the interior or center cavity 8 of the arcs 2 and 4. Arcs2 and 4 have angular dimensions greater than 180. Advantageously thedimensions of arcs 2 and 4 can be in the neighborhood of 300 so that gap6 has an angular dimension of approximately 60 when arcs 2 and 4 arealigned as shown. The desired dimension of gap 6 will of course dependupon the size of the cable or other object about which arcs 2 and 4 areto be placed. The angular dimensions of arcs 2 and 4 are made as largeas possible consistent with this desired dimension of gap 6. Arcs 2 and4 can be made identical to each other if desired to obtain manufacturingeconomies.

The mating faces 10 and 12 of arcs 2 and 4, respectively, are smooth andplanar to allow close mating for good magnetic coupling therebetween.Each face 10 and 12 has an arcuate groove 14 and 16, respectively,therein extending the full angular extent of the face. Mounted withingrooves 14 and 16 is a rail or arcuate member 18 which has an angulardimension equal to that of arcs 2 and 4. Rail l8 advantageouslycomprises an arc of low friction material such as the synthetic resinpolymer commercially available under the trademark TEFLON which allowsarcs 2 and 4 to readily rotate with respect to each other along rail 18.The outer face 22 of arc 4, and also the outer face 20 of are 2 if thearcs are identical includes small depressions or dimples 24 therein forpurposes to be subsequently explained. The inner surfaces 44 and 46 ofarcs 2 and 4, respectively, include grooves or recesses 45 and 47 spacedapproximately 180 apart thereabout for uses to become clearersubsequently.

FIG. 2 shows a holder or snap ring 30 which is adapted to hold arcs 2and 4 in mating relationship on rail 18. Ring 30 includes an arcuateflange or wall 32 having upstanding ribs or fingers 34 along both edgesthereof. Wall 32 advantageously has an angular dimension substantiallyequal to that of arcs 2 and 4. Wall 32 includes two upstanding tabs 36on the ends 38 thereof which extend slightly less than half way acrossthe width 40 of wall 32 to prevent are 4 from rotating with respect toholder 30. Two of the upstanding fingers 35 along one edge of wall 32include beads or protrusions 42 formed thereon and adapted to mate withdimples 24 on are 4 to provide a further locking or detenting actiontherewith. The outside surface 48 of ring 30 includes two hubs or ridges49 which are adapted to fit within grooves 45 and 47 when these groovesare aligned to provide a locking or detenting action for locking arcs 2and 4 in position'with respect to each other. I-Iubs 49 are locatedapproximately 180 degrees apart on surface 48. Ring 30 advantageouslycan be formed from a spring metal.

Ring 30 is placed within center cavity 8 so that the inner surfaces 44and 46 of arcs 2 and 4, respectively, lie along the outside surface 48of wall 32 with fingers 34 upstanding along outer faces 20 and 22 tohold arcs 2 and 4 in mating relationship on rail 18 as is shown in FIG.3. Tabs 36 contact the end faces 52 of are 4 and a portion of rail 18and beads 42 mate with dimples 24 to hold or lock arc 4 and rail 18stationary with respect to ring 30. Tabs 36 do not contact the end faces50 of are 2. Thus arc 2 can rotate with respect to ring 30, arc 4 andrail 18 along the rail 18 while faces 10 and 12 remain in close matingcontact. When arcs 2 and 4 are aligned with each other, i.e., when theend faces 50 and 52 lie in substantially the same plane, hubs 49 alsomate with grooves 45 and 47 to provide a detenting or locking action tohold arcs 2 and 4 aligned. Thus the arcs can be placed about acontinuous cable or the like by passing the cable through slot or gap 6.

After arcs 2 and 4 are placed about the cable, gap 6 is closed byapplying a moment to are 2. When sufficient moment is applied, thedetent force between hubs 49 and grooves 45 in arc 2 is overcomeallowing arc 2 to rotate on rail 18 with respect to are 4 as shown inH0. 4. Arc 2 advantageously is rotated 180 at which time grooves 45 and47 are again aligned and hub 49 again engages these grooves to lock thearcs about the cable with gap 6 closed and with a substantial area ofcontact between arcs 2 and 4 to provide good magnetic couplingtherebetween as shown in FIG. 5.

The magnetic core apparatus of this invention can quickly and easilyinstalled or removed from cables by a twisting motion which moves arcs 2and 4 into and out of alignment as required. This offers significanteconomies over existing split core apparatus.

The close mating of arcs 2 and 4 along faces 10 and 12 and thesubstantial angular dimension of these arcs provides very good magneticcoupling between the arcs so that the arcs present a substantiallycontinuous circular magnetic path about an enlcosed cable. This is asignificant advantage over split core apparatus which present magneticpath discontinuities at abutting ends of arcs of relatively smallangular dimensions.

While the invention has been described with reference to a specificembodiment thereof, it is to be understood that various modificationsthereto might be made without departing from the spirit and scope of thefollowing claims.

What is claimed is:

1. Magnetic core apparatus adapted for installation about conductorshaving no accessible end, comprising, in combination:

first and second arcs of magnetic material each having an angulardimension of greater than 180 each of said arcs including asubstantiallyplanarface having an arcuate groove therein; an arcuaterail installed in said grooves for rotatably mounting said arcs withrespect to each other with said planar faces in opposing matingrelationship; and I a holder mounted about said arcs for holding saidarcs in said mating relationship and including two upstanding flangesthereon which hold said first arc and said rail stationary with respectto said holder while permitting said second arc to rotate with respectto said holder, whereby said second arc can be rotated into alignmentwith said first arc to produce a gap by which said apparatus can beinstalled about said conductors, and said gap can be closed by furtherrotation of said second arc.

2. Apparatus in accordance with claim 1 wherein said angular dimensionof said arcs is substantially 300.

3. Apparatus in accordance with claim 1 wherein said arcs includeinterior surfaces contacting said holder and having depressions formedtherein, and said holder includes protrusions thereon adapted to matewith said depressions and hold said arcs in preselected positions withrespect to each other.

4. Apparatus in accordance with claim 3 wherein said depressions andsaid protrusions are spaced 180 apart on said'arcs and said holder,respectively, so that said arcs can be held in first and secondpositions wherein said gap is fully open and fully closed, respectively.

5. Apparatus in accordance with claim 1 wherein said rail comprises anarc of low friction material to facilitate rotation of said arcs withrespect to each other.

6. Apparatus in accordance with claim 1 wherein said holder comprises anarcuate wall having an angular dimension substantially the same as saidangular dimension of said arcs, and upstanding fingers along the edgesof said wall for receiving said arcs therebetween to hold with respectto said holders.

1. Magnetic core apparatus adapted for installation about conductorshaving no accessible end, comprising, in combination: first and secondarcs of magnetic material each having an angular dimension of greaterthan 180* each of said arcs including a substantially planar face havingan arcuate groove therein; an arcuate rail installed in said grooves forrotatably mounting said arcs with respect to each other with said planarfaces in opposing mating relationship; and a holder mounted about saidarcs for holding said arcs in said mating relationship and including twoupstanding flanges thereon which hold said first arc and said railstationary with respect to said holder while permitting said second arcto rotate with respect to said holder, whereby said second arc can berotated into alignment with said first arc to produce a gap by whichsaid apparatus can be installed about said conductors, and said gap canbe closed by further rotation of said second arc.
 2. Apparatus inaccordance with claim 1 wherein said angular dimension of said arcs issubstantially 300*.
 3. Apparatus in accordance with claim 1 wherein saidarcs include interior surfaces contacting said holder and havingdepressions formed therein, and said holder includes protrusions thereonadapted to mate with said depressions and hold said arcs in preselectedpositions with respect to each other.
 4. Apparatus in accordance withclaim 3 wherein said depressions and said protrusions are spaced 180*apart on said arcs and said holder, respectively, so that said arcs canbe held in first and second positions wherein said gap is fully open andfully closed, respectively.
 5. Apparatus in accordance with claim 1wherein said rail comprises an arc of low friction material tofacilitate rotation of said arcs with respect to each other. 6.Apparatus in accordance with claim 1 wherein said holder comprises anarcuate wall having an angular dimension substantially the same as saidangular dimension of said arcs, and upstanding fingers along the edgesof said wall for receiving said arcs therebetween to hold said arcs insaid mating relationship on said rail.
 7. Apparatus in accordance withclaim 6 wherein said fingers contact said arcs along exterior surfacesthereof, said exterior surfaces including depressions formed therein,and selected ones of said fingers include dimples therein for matingwith said depressions in one of said arcs for holding said one arcstationary with respect to said holders.